1. Dauphin Island Memories……
Mecha Streisand

2. Competition (Ch. 10) Ken Jennings: my hero! 74 wins (2004)
$2.52 million

3. DeWit Replacement Series
After growing, determine output ratios
Ex:
# seeds A:# seeds B
biomass A:biomass B

4. DeWit Replacement Series
After growing, determine output ratios
Ex:
# seeds A:# seeds B
biomass A:biomass B
Graph input & output ratios (log scale)
log output A:B
log input A:B

5. DeWit Replacement Series
No interaction, input ratio=output ratio
Stability line. Slope=1
Ex: 50:50 input & output ratios
Stability line
50:50 X
log output A:B
50:50
log input A:B

6. DeWit Replacement Series
Area above stability line?
Stability line X
log output A:B
log input A:B

7. DeWit Replacement Series
Area above stability line: “A wins zone”
More A output than input
Ex: 50:50 input, 75:25 output
Stability line
75:25 X
log output A:B
50:50
log input A:B

8. DeWit Replacement Series
Area below stability line?
Stability line
log output A:B X
log input A:B

9. DeWit Replacement Series
Area below stability line: “B wins zone”
More B output than input
Ex: 50:50 input, 25:75 output
Stability line
log output A:B
25:75 X
50:50
log input A:B

10. DeWit Replacement Series
Movement on graph
Suppose take output (X) & plant again
Stability line
75:25 X
log output A:B
50:50
log input A:B

11. DeWit Replacement Series
Movement on graph
Suppose take output (X) & plant again
95:5 Y
Stability line
75:25 X
log output A:B
75:25
50:50
log input A:B

12. DeWit Replacement Series
Movement along line (experimental line)
A better competitor & eliminate B
95:5 Y
Stability line
75:25 X
log output A:B
75:25
50:50
log input A:B

13. DeWit Replacement Series
If line above stability line, move left to right
Stability line
log output A:B
log input A:B

14. DeWit Replacement Series
If line below stability line, move right to left
Stability line
log output A:B
log input A:B

15. DeWit Replacement Series
Ex results (4 possible):
Stability line
log output A:B
log input A:B

16. DeWit Replacement Series
Ex results:
Slope = 1 above stability line A
Stability line
log output A:B
log input A:B

17. DeWit Replacement Series
Ex results:
Slope = 1 below stability line B
Stability line
log output A:B
log input A:B

18. DeWit Replacement Series
Ex results:
Slope <1
Lo input ratios A wins:
Stability line
log output A:B
log input A:B

19. DeWit Replacement Series
Ex results:
Slope >1
Stability line
log output A:B
log input A:B

20. DeWit Replacement Series
More complicated designs: change ratio and density
Replacement
Series
Partial
Additive
Series
Additive
Series
Complete
Additive
Series

21. DeWit Replacement Series
How helpful?
Ex, wild oats (Avena)
CA annual grassland
Mediterranean climate
Tule Elk

22. DeWit Replacement Series
Greenhouse results (dotted line): Outcome?
A) wild oat wins
B) slender wild oat wins
C) 1 stable ratio
D) either wins (which depends on input ratio)

23. DeWit Replacement Series
Field trials: >

24. Studying Competition Field approach: removal experiment
Remove
Ex: target-neighborhood experiment

25. Target-neighborhood experiment
Ex: creosote bush (Larrea tridentata) & burro bush (Ambrosia dumosa)
Mojave Desert

26. Target-neighborhood experiment
Remove around “target” shrub
Target monitored (water status)

27. Target-neighborhood experiment
Remove around “target” shrub
Target monitored (water status)
Result:
Danger…

28. Danger for removal experiments: Apparent competition
Herbivore effects mimic competition
Ex: Herbivore eats A and B

29. Other points 1) Herbivory influences competition
Ex, chalk grassland (England)
Lab studies: grass better competitor. How forbs persist?
Rabbits (“killer rabbits?”)
Plant Ecology Theatre!

30. Other points Rabbits prefer grass (help forbs)
Twist: Myxomatosis decimated
The marsh fritillary

31. Other points 2) Disturbance timing on competition species 1 numbers
No disturbance
time

32. Other points Can allow coexistence Frequent disturbances numbers
species 1
species 2
time

33. Other points
3) Phenology can